Pier installation with .7m raised decking in place

[8324689]

Hello all I'm about to embark on trying to decouple my pier from my raised decking. 

I have had two ideas but I'm sure some people here will have some more experience and better ideas 

The decking is raised by approx .7m off the ground which complicates things. It is loose soil undernesth a blackout sheet in which I can rip and dig into the soil. 

Please see the video so you see how the setup works with the trap door. 

We may be moving from this house so I don't want to put too much work into it if poss....!

 

Option A)

I could neatly take one decking panel off and fit 150 mm tube down from the top of the decking surface and feed a steel lintel through and fill with concrete. The only thing about this is that I will be using the full 3 m of the 150 mm tube (.7m underground, .8m overground and underneath decking, 1.2m over decking)

I'm guessing my hole underneath the decking will need to be about .7 m  for sturdiness. Needless to say it's hard to get access down there but possible. In fact I think the deepest I could dig will be the length of my arm in order to extract the soil.  I would use my Altair pier top but alas my pier would be redundant then. Which is okay, I can save it in case we move rurally. 

Like this

https://www.skyatnightmagazine.com/advice/how-to-build-a-back-garden-telescope-pier/

 

Option B )

I could make a concrete base and build up the concrete plinth to come all the way up to the decking but I will use a hell of a lot of concrete. And take up the space of two decking panels. The advantage there is I could use my pier that I own already in the pictures. 

 

I think I'm going to do option A but if anyone has any better ideas please chip in

 

Many thanks as always 

 

IMG_5986.MOV

 

 

 

Edited January 10, 2022 by 8324689

[AstroKeith]

Another option would be to build a frame below the decking to spread the load over a wider area, perhaps like a wide, 0.7m high 'tripod'. This could sit on three concrete pads that needn't be so deep.

The top of the 'tripod' would be just below the surface of your decking, so your current pier can be bolted to it, and pass through your decking.

It could be made from timber or steel.

[8324689]

Thanks for this and great idea. Thing is, the ground is so uneven and sloped (you might see this on the video) it could be more work than option A 

[mikeDnight]

I think I'd be inclined to dig out an approximate cubic yard of soil beneath your decking. Insert a steel pier and pack the hole with rubble and concrete. I may even fill the steel pier with rubble and concrete, or sand and cement just to add a bit more solidity. That's what I did with my home made 6" square steel pier, and its as solid as I could wish for. It could carry anything! I left a 1/2" gap between the wooden floor of my observatory and the pier itself, just so vibration from walking around didnt impact the telescope. If you did move house in the future, just stick a bird table on top of it and the new residents will love it; that is until they try moving it. 

[8324689]

15 minutes ago, mikeDnight said:

I think I'd be inclined to dig out an approximate cubic yard of soil beneath your decking. Insert a steel pier and pack the hole with rubble and concrete. I may even fill the steel pier with rubble and concrete, or sand and cement just to add a bit more solidity. That's what I did with my home made 6" square steel pier, and its as solid as I could wish for. It could carry anything! I left a 1/2" gap between the wooden floor of my observatory and the pier itself, just so vibration from walking around didnt impact the telescope. If you did move house in the future, just stick a bird table on top of it and the new residents will love it; that is until they try moving it. 

Looks great! I think you essentially describing option a?

 

Thanks 

[7170]

I would personally do what @AstroKeith suggests. Maybe dig four 25cm wide x 40cm deep holes in the ground for concrete footings and build a metal/wood frame under the current deck with a metal plate on time and fix onto that.  Give the access and difficulty of digging in the space I would not want to try and did a single deep hole!

Edited January 10, 2022 by 7170

[8324689]

2 hours ago, 7170 said:

I would personally do what @AstroKeith suggests. Maybe dig four 25cm wide x 40cm deep holes in the ground for concrete footings and build a metal/wood frame under the current deck with a metal plate on time and fix onto that.  Give the access and difficulty of digging in the space I would not want to try and did a single deep hole!

Hmm ok sure thing thanks am thinking  about this .......but Im just having trouble visualising how this could actually be really sturdy (and be cheap!!)

Edited January 10, 2022 by 8324689

[Swoop1]

I would be tempted to go option A but remove a few more decking sections to give working room.

[7170]

55 minutes ago, 8324689 said:

Hmm ok sure thing thanks am thiking about this .......but Im just having trouble visualising how this could actually be really sturdy (and be cheap!!)

I don't know if links are permitted on SGL - but it is from another SGL page so I assume it is ok - image link. If you look at the tripod looking bit under the column, it is effectively this I would create under your current patio level. So the weight and angular force is spread out over a larger area. It is like a two pillar car lift, you don't fix them onto a very deep piece of concrete but instead a strong (not so thick) slab that spreads the load well over a larger area.

 

 

[8324689]

13 minutes ago, 7170 said:

I don't know if links are permitted on SGL - but it is from another SGL page so I assume it is ok - image link. If you look at the tripod looking bit under the column, it is effectively this I would create under your current patio level. So the weight and angular force is spread out over a larger area. It is like a two pillar car lift, you don't fix them onto a very deep piece of concrete but instead a strong (not so thick) slab that spreads the load well over a larger area.

 

 

. I get the idea of spreading the weight but it doesn’t make sense to me how to apply that picture to my position.
I either use the pier I have. Or don’t use the pier I have and use a cheap 150 mm piping

Really trying to keep budget at absolute minimum!

 

 Thanks 

[8324689]

26 minutes ago, Swoop1 said:

I would be tempted to go option A but remove a few more decking sections to give working room.

Yes maybe I just go with it and see how deep I can get and then think about temporarily removing planks

[8324689]

Hmmmm

what if I was to raise a normal HEQ5 tripod on parallel large planks of wood distributing the weight. If I was doing polar alignment hopefully they have your planks would think lower and the fireplace would keep the tripod unaffected. An experiment to see….